Staged Phase 3 Study to Assess the Safety and Immunogenicity of Ebola Candidate Vaccines Ad26.ZEBOV and MVA-BN-Filo

This is staged Phase 3 study to gather information on the safety and immunogenicity of a 2-dose heterologous regimen. In this regimen, Ad26.ZEBOV will be administered as a Dose 1 vaccination followed by the candidate vaccine MVA-BN-Filo (Dose 2 56 days later) and a booster dose of A26.ZEBOV will be administered 2 years post Dose 1 vaccination to participants in Stage 1 who consent to this. The study will take place in Sierra Leone and will consist of a screening phase, an active phase (vaccination) and a follow-up phase. The active phase of the study will be conducted initially in two stages. In the first stage approximately 40 adults aged 18 years or older will be vaccinated to gain information about the safety and immunogenicity of the 2-dose heterologous vaccine regimen. In stage 2 a larger group of approximately 976 individuals will be vaccinated to further evaluate the safety and immunogenicity of the 2 dose heterologous vaccine regimen across different age groups. In this stage, children aged 1 year or older, adolescents and adults will be included. Solicited local and systemic adverse events will be collected until 7 days after the Dose 1 and Dose 2 vaccination. Unsolicited adverse events will be collected from signing of the informed consent form (ICF) onwards until 56 days after the Dose 2 vaccination in Stage 1 and then again from the day of the booster vaccination until 28 days after the booster vaccination, and until 28 days after each vaccination in stage 2. Serious adverse events will be collected from signing of the ICF onwards until 12 and 36 months after the Dose 1 vaccination in Stage 2 and Stage 1, respectively. These data will be reviewed by an independent data monitoring committee (IDMC) to assess whether initiation of vaccination in the next stage or age group can be provided. Safety evaluations will include assessment of adverse events, which will be monitored throughout the study. Participants in Stage 2 will be followed up for safety and immunogenicity until 12 months (children and adolescents) or 24 months (adults) after the Dose 1 vaccination. Participants in Stage 1 will be followed up for safety and immunogenicity until 36 months after the Dose 1 vaccination or until 1 year after the booster vaccination.